A conventional oil pan for combustion machines is composed of a plurality of sheet metal components which are welded to one another. Since a large number of welds is required, it has been proposed to use extrusions for the oil pan. This allows the number of components to be reduced and makes it possible to decrease the weight and improve the dimensional accuracy of the oil pan.
A known oil pan of the type containing extrusions is provided with flanges for connecting the oil pan to a crankcase. Covers are arranged at the ends of the oil pan and partitions are disposed internally thereof. The partitions are secured to the walls of the oil pan and extend transversely of the latter.
The development of high output engines has increased the amount of oil required for reliable lubrication and adequate heat removal. However, a large amount of oil necessitates a large oil pan volume which imposes additional requirements on the stiffness of the oil pan and its resistance to vibration.
The surges which occur with a large amount of oil also generate particularly large loads. In conjunction with the vibrations from the engine, these loads can impose undue stresses on the oil pan joints. It has been found that cracks frequently appear at the joints between the relatively stiff oil pan walls and the flexible partitions. These cracks can lead to joint failure and resulting engine damage.